This old HEATHKIT AA-14 was essentially dead in one channel. Signal injection and tracing led to the very first stage of the left channel. New electrolytic coupling caps restored both the AUX in and PHONO preamp stage. Thorough cleaning of the SOURCE rotary switch and pots and new speaker output capacitors finished it up. It is a nice little amp with mono selections for both AUX and PHONO which you don't get much anymore.